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</div><hr /><div id="intro.cairo" class="preface">
  <h1 class="title">简介</h1>
  <p class="para">
   Cairo is a native PHP extension to create and modify graphics using the Cairo
   Graphics Library.
  </p>
  <p class="para">
    The Cairo Graphics Library is a 2D library written in C with support for
    multiple output devices. Currently supported output targets include the X
    Window System, Quartz, Win32, image buffers, PostScript, PDF, and SVG file
    output. Experimental backends include OpenGL (through glitz), XCB, BeOS,
    OS/2, and DirectFB. The library also has support for two types of text
    manipulation and layout. The &quot;toy&quot; API provides demo quality support, and
    the glyphs API, although full-featured, works best with a helper library
    such as pango.  Font backend support includes FreeType, Quartz, Win32, and
    User fonts.
  </p>
  <p class="para">
   There are two types of computer graphics, vector and raster. Raster graphics
   are the representation of images as an array of pixels. Vector graphics use
   geometrical primitives such as points, lines, curves or polygons to represent
   images. The primitives are created using mathematical equations. The Cairo
   Graphics Library takes a vector approach to graphics, allowing smaller size,
   infinite zooming, and moving, scaling and rotating without degrading image
   quality.
  </p>
  <p class="para">
   Operations in the cairo graphics library including stroking and filling cubic
   Bézier splines, transforming and compositing translucent images, and
   antialiased text rendering. All drawing operations can be transformed by any
   affine transformation (scale, rotation, shear, and others) This is very
   similiar to drawing operations for PostScript and PDF drawing.
  </p>
  <p class="para">
    The Cairo PHP Extension aims to provide support for all officially supported
    font backends and surface backends, as well as expose all available
    functionality in cairo to PHP users.
  </p>


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